BOSTON — Successful perennial gardeners are a lot like orchestra conductors.
They must possess impeccable timing - especially during the planting season. If they don't know when certain perennials they've planted are going to bloom, there will be long, colorless gaps that disrupt the harmony of their gardens.
Most perennial gardens are designed to feature various blooms, along with a lush accompaniment of spring bulbs, summer grasses, and a background of evergreens.
The idea is to showcase a variety of colors in successive crescendos throughout the growing season: from the snowdrops of early spring to the asters of autumn.
"Perennial gardens are wonderful because they challenge you to be creative during the planting season," says garden expert Karen Strohbeen. "Gardeners must also have a firm grasp on when certain plants hit their peak as well as a good place to position them."
Mrs. Strohbeen's 13-part gardening series, "The Perennial Gardner," premiered Saturday, April 10, on PBS (check local listings for future broadcasts).
"When done well, a perennial garden can be very dramatic - as beautiful to look at as one of Monet's garden impressions," Strohbeen says.
Perennials are plants that renew themselves each year. Trees, bulbs, lawns, ferns, and flowers like primrose, chrysanthemum, and poppy are are considered perennials. A few varieties of vegetables are as well.
Strohbeen takes an artful yet practical approach to perennial gardening. Her show, taped at her gardens in southwest Iowa, demonstrates gardening basics that can be applied to almost all types of perennial gardens throughout the country.
Strohbeen gently presents useful tips for both serious and casual gardeners. And she frequently visits with a variety of gardening experts who share their skills and knowledge.
Although each show has a different theme - "Pretty Onions," and "Mixed Gardening," for example - the series emphasizes starting and caring for perennial gardens.
So how does a gardner plan and care for a perennial garden? "Getting to know the plants is the key," Strohbeen says. "A good gardener will plant a mix of annuals and biennials alongside their perennials. Talk to your local nursery about when the perennials you have chosen will bloom, peak, and finish flowering."
Strohbeen says perennials that bloom at relatively the same time look best grouped together. Typically, she says, four such groupings are planted near one another to provide color in successive peaks during the growing season.
For instance, a bed that will peak in the spring is planted with soft pastel shades while a different bed that will peak during the summer is planted to both accentuate the warmth of the season and contrast with the heat of midsummer by using cool lavender, blue violet, and lemon-yellow flowers.
Grouping together dissimilar, or directly contrasting, flower colors is visually exciting, she says. The violet campanula, for example, makes the yellow hemerocallis "Condilla" appear dazzlingly bright.
Unusual leaf color can also play a part in the most intriguing combinations: gold, silver, copper, purple, lime, and blue. Golden foliage, for instance, gives the illusion of dappled sunlight and lift colors around it, she says.
To the beginner perennial gardener, Strohbeen says "Keep it as simple as possible. Ask your nursery to help you select perennials that are aren't fussy - ones that are easy to care for and mix well with each other and the region."
Strohbeen also says that garden novices should never buy too many of the same plants at one time. "Just buy a one and see how it grows in your garden," she advises. "If it does well, buy more."
She also offers advice for the seasoned green thumb:
"When a fellow gardener shows a particular interest in a specimen in your garden," she says, "don't hesitate to snip off a clipping and give it to them. You are sharing something special and beautiful that you've grown."
*John Christian Hoyle is on the Monitor staff.